Characterization of forehead blood flow bias on NIRS signals during neural activation with a verbal fluency task. (January 2023)

• Record Type: Journal Article
• Authors: Seiyama, Akitoshi; Miura, Tatsuro; Sasaki, Yuji; Okahashi, Sayaka; Konishi, Nami; Cassim, Monte
• Is Part Of: Neuroscience research. Volume 186(2023)
• Page Start: 43
• Page End: 50
• Publication Date: 2023-01
• Subjects: Near infrared spectroscopy -- Forehead scalp blood flow -- Cerebral blood flow -- Modified Beer-Lambert Law -- Hemodynamic separation method -- Verbal fluency task; Neurosciences -- Research -- Periodicals; Neurosciences -- Research -- Japan -- Periodicals; Neurology -- Periodicals; Neurosciences -- Periodicals; Neurosciences -- Recherche -- Périodiques; Neurosciences -- Recherche -- Japon -- Périodiques; Neurosciences -- Research; Japan; Periodicals; 612.8
• DOI: 10.1016/j.neures.2022.09.012
• Languages: English
• ISSNs: 0168-0102

Abstract

Abstract: The major problem of near-infrared spectroscopy (NIRS) for brain activity measurement during verbal fluency task is the overlapping forehead scalp blood flow (FBF) on the target cerebral blood flow (CBF). There could be among-individual differences in the influence of FBF on CBF. We investigated effects of FBF on CBF by comparing signals obtained through a laser Doppler flowmeter (LDF) and NIRS using the modified Beer-Lambert Law (MBLL). Among 25 healthy individuals, 7 participants showed a strong correlation between LDF and NIRS signals ( r s >0.500). There were no significant differences according to age or sex. Subsequently, we applied the hemodynamic separation method to the values calculated using the MBLL (Δ[oxy-Hb]M ): to separate the concentration of oxygenated hemoglobin in the forehead (Δ[oxy-Hb]F ) and cerebral cortex (Δ[oxy-Hb]C ). First, we found that the influence of Δ[oxy-Hb]F on Δ[oxy-Hb]C in the high r s group was almost twice as large as that in the low r s group. Second, presence of sex and age differences in the influence of Δ[oxy-Hb]F on Δ[oxy-Hb]C were suggested. Based on the results, we discuss the factors affecting FBF and the resulting variations in NIRS signals. Highlights: Separation of the forehead scalp blood flow and the cerebral blood flow. Factors affecting the forehead scalp blood flow during verbal fluency task. Sex effect of the forehead scalp blood flow on the cerebral blood flow. Age effect of the forehead scalp blood flow on the cerebral blood flow.